Robotic all terrain surveyor

ABSTRACT

A vehicle including a body and three legs. Each leg includes a proximal end coupled to the body, a distal end opposite the proximal end, and an actuator. Each actuator imparts enough acceleration to the vehicle along an axis of the leg to cause the distal end of the leg to leave a surface upon which it rests. Thus, the robot can pivot around one leg when the actuator of another leg imparts an acceleration. One actuator may also cause two legs to leave the surface. Moreover, the actuators may be spring biased into a retracted position. Further, the body may be a Platonic solid and the axes of the lags may pass through the vehicle&#39;s center of gravity. Of course, the body could be a sphere while the vehicle could be a planetary robot or a toy. Methods of traversing a surface are also provided.

FIELD OF THE INVENTION

This invention relates generally to all-terrain vehicles and, moreparticularly, to all terrain vehicles for traversing surfaces that arelikely to include obstructions.

BACKGROUND OF THE INVENTION

Many tasks expose human workers to adverse, or hostile, environmentalconditions. Fighting fires, repairing underwater structures,reconnoitering an area, exploring planets, rescuing hostages andstranded people, and attacking enemy positions expose the personnelinvolved to a variety of risks to life and limb. For some time nowrobots have been employed to accomplish portions of these tasks. Somerobots are simply equipped with wheels or tracks and can only operate onflat, unobstructed surfaces. Even the presence of small obstacles,ledges, steps, ravines and the like disable these simple devises. Morecomplex wheeled robots, like the Mars rovers of recent years, have theirwheels mounted on arms that allow the wheels some freedom to movevertically. Yet these robots may still become hung up on largerobstacles. Biologically inspired bipedal robots have also beenintroduced in an effort to overcome obstacles. These bipedal robotsinclude complex leg mechanisms that mimic the walking motion of a humanbeing. The software required to operate these mechanisms is quitecomplex and can do nothing to save the robot should it be toppled.

Also, because many robots use air-breathing engines for power theycannot be used in space or underwater. The use of environmental air forcombustion also poses problems if the robot should enter an environmentcontaminated by airborne chemicals (e.g. pollution, poisoning, smoke,etc.) Many of these substances can clog air filters or attack the hotinterior surfaces of the engine and thereby precipitate failure of theengine. Further, many currently available robots use their onboard powersupplies inefficiently thereby precluding long missions. Theinefficiency is in part due to the need for the robot to run the engineeven while loitering to have power available in case a disturbanceattempts to topple the robot.

Despite the problems with currently available robots, the need forrobots has often been cited by many private and public organizations.Therefore a need exists for efficient robots capable of navigatingaround obstacles and escaping from traps.

SUMMARY OF THE INVENTION

It is in view of the above problems that the present invention wasdeveloped. The invention provides apparatus and methods for traversingsurfaces, particularly rough surfaces such as those encountered duringplanetary exploration, reconnaissance, or rescue missions.

A first preferred embodiment of the present invention provides a smalltactical robot. The robot has a spherical body and a plurality of legsextending about the periphery of the body in a manner similar to that ofthe spines of a sea urchin. For energy, a tank onboard the robotcontains an energy rich fuel (e.g. hydrogen peroxide) that is convertedto hot gas by a catalyst bed to drive the robot. By decomposing thefuel, as opposed to combusting the fuel, the need for combustion airdrawn from the environment is eliminated. The hot gas drives two-strokeactuators positioned in each of the legs of the robot that, preferably,work in a manner similar to a gas driven pogo-stick. When the hot gasenters the actuator, the gas attempts to drive a piston of the actuatorout and away from the body. In turn, the piston pushes against thesurface upon which it (and the robot) rests and accelerates the robotaway from the surface. If the acceleration is great enough, the robotbecomes airborne (i.e. the robot leaves the surface). Because theactuated leg is usually not perpendicular to the surface, the robot willtraverse some distance across the surface while in the air. Thus, therobot moves by hopping around on its legs and can therefore overcomeobstacles and escape from traps.

In a second preferred embodiment, the present invention provides avehicle that includes a body and three or more legs. Each leg includes aproximal end coupled to the body, a distal end opposite the proximalend, and an actuator. Each actuator imparts enough acceleration to thevehicle along a longitudinal axis of the leg to cause the distal end ofthe leg to leave the surface upon which it rests. Thus, the robot canpivot around one leg when the actuator of another leg imparts anacceleration. One actuator may also cause two legs to leave the surface.Moreover, the actuators may be spring biased into a retracted position.Further, the location of the robot's legs may be based on a Platonicsolid (e.g. a tetrahedron, hexahedron or cube, octahedron, dodecahedron,or icosahedron) and the axes of the legs may pass through the vehicle'scenter of gravity. Of course, the body could be a sphere while thevehicle itself could be a planetary exploration robot or a toy.

In a third preferred embodiment, the present invention provides a methodof traversing a surface. Generally, the method includes determiningwhich legs of a multi-legged vehicle are resting on a surface,determining in which direction to proceed, and imparting an accelerationto the vehicle using one of the legs. The imparted acceleration causesat least one leg to leave the surface upon which the leg rests. Thus,obstacles on the surface maybe hopped over. Alternatively, the vehiclecan pivot around a leg other than the one imparting the acceleration.

In another preferred embodiment, the present invention provides a robotthat includes a body having the shape of a dodecahedron and 12 legscorresponding to each of the 12 faces of the dodecahedron. Each legincludes a proximal end coupled to the body at the center of one of thefaces. Further, each leg is perpendicular to the face to which it iscoupled and includes an actuator. Also, the robot includes a controlmechanism or circuit that causes at least one of the actuators to impartan acceleration to the robot.

Further features and advantages of the present invention, as well as thestructure and operation of various embodiments of the present invention,are described in detail below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand together with the description, serve to explain the principles ofthe invention. In the drawings:

FIGS. 1A to 1E show several embodiments of robots constructed inaccordance with the principles of the present invention;

FIGS. 2 a to 2 c illustrate side elevation views of a robot constructedin accordance with a preferred embodiment of the present invention asthe robot traverses a surface;

FIGS. 3 a to 3 b illustrate top plan views of a robot of anotherpreferred embodiment as the robot traverses the surface.

FIG. 4 illustrates another robot constructed in accordance with apreferred embodiment of the present invention;

FIGS. 5A and 5B illustrates a leg of a robot constructed in accordancewith another preferred embodiment of the present invention;

FIG. 6 illustrates a block diagram of an architecture of a robotconstructed in accordance with another preferred embodiment of thepresent invention; and

FIG. 7 illustrates a method in accordance with a preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings in which like reference numbersindicate like elements, FIGS. 1A to 1E show several embodiments ofrobots constructed in accordance with the principles of the presentinvention.

FIG. 1A shows the robot 10 resting on a surface 12. The surface 12 couldbe any surface such as terrain on the Earth, the Moon, Mars, or othercelestial bodies. In the alternative, the surface 12 could also be afloor of a room, or a deck of a ship or aircraft. Thus, the nature ofthe surface 12 does not restrict the scope of the invention. Typically,the surface 12 includes obstacles such as large rocks 14 or chasms 16that would likely cause conventional robots to become trapped by, orstuck on, the obstacles 14 or 16. As will be described, the robot 10 isable to hop over these obstacles 14 and 16 and otherwise traverse thesurface 12.

With continuing reference to FIG. 1A, the robot 10 includes a body 18and a plurality of legs 20. In the current embodiment, the robot 10 has3 legs 20A, 20B, and 20C. Each leg 20 defines a longitudinal axis 22that runs between the proximal end 24 and the distal end 26 of the leg20. The robot 10 also includes a center of gravity 28 that may becoincident with the center of gravity of the body 18. In general, thelegs 20 are distributed about the periphery of the body 18. Moreparticularly, the three legs 20A, 20B, and 20C of the present embodimentare shown spaced about the lower half of the body 18. Each leg 20 ispreferably rigidly coupled to the body 18 at the proximal end 24 in sucha manner that the longitudinal axis 22 extends through the center ofgravity 28 of the robot. Though, other embodiments provide robots 10 inwhich the longitudinal axis may extend above (or below) the center ofgravity 28. Further, additional legs 20 can be included on the robot 10.For example, one preferred embodiment as shown in FIG. 1B includes fourlegs. The body shown in FIG. 1B comprises a tetrahedron with four faces29 with each leg being coupled to the body at the face and projectingfrom the face such that the longitudinal axis 22 of the leg extendsthrough the center of gravity 28 of the body 10. FIG. 1C shows analternate embodiment where the body 10 comprises a hexahedron with sixlegs coupled to the body at each face of the body. FIG. 1D shows analternate embodiment where the body comprises a dodecahedron with twelvelegs extending from each of the faces of the body. FIG. 1B shows anotheralternate embodiment of the body comprising an icosahedron comprisingtwenty faces and twenty legs with each of the twenty legs being coupledto the body and extending from a respective face.

In operation, each leg 20 is able to impart an acceleration to the robot10 along the longitudinal axis 22. More particularly, the accelerationprovided by the leg 20 is sufficient to propel the distal end 26 of theleg 20 away from the surface 12 and preferably sufficient to propel theentire robot 10 away from the surface 12 in the direction of thelongitudinal axis 22. Thus, when it is desired for the robot 10 to move,one leg 20 accelerates the robot away from the surface 12 in thedirection of the y-component 22Y of the longitudinal axis 22 and alongthe surface 12 in the direction of the x-component 22X of thelongitudinal axis 22. While, the components 22X and 22Y of thelongitudinal axis are shown as being horizontal and vertical,respectively, no such limitation is implied regarding the scope of thepresent invention. Rather, the components 22X and 22Y merely designate adirection generally parallel and generally perpendicular to the surface12, respectively, at the point where the leg 20 rests on the surface 12.

If it is desired for the robot 10 to traverse the surface 12 beyond theposition of the obstacle 14, the leg furthest from the rock 14 (here leg20B) is used to propel the robot 10 along the longitudinal axis 22B.Upon leaving the surface 12, the robot 10 hops over the rock 14 along agenerally ballistic path. Further, as shown by FIG. 1A, at times theorientation of the robot 10 will be such that no one leg 20A, 20B, or20C is directly opposite the chasm 16. In these situations the legs 20Aand 20C that are most directly opposite the chasm 16 (relative to thecenter of gravity 28) operate in combination to propel the robot 10 overthe chasm 16. Those skilled in the art, will recognize that the forceimparted by each of the legs 20A and 20C will have x and y components aswell as a z component directed into, or out of, the page. By choosingwhich legs 20 are to propel the robot 10, and choosing the amount offorce to be applied by each leg 20, it is possible to direct the robot10 in any direction in the x-z plane. In a similar manner it is alsopossible to determine how far above the surface 12 the robot 10 ispropelled. Thus, the trajectory of the robot 10 can be tailored to thespecific needs of a particular mission or specific maneuver. The abilityto tailor the trajectory is particularly useful in crowded environmentsor where the robot 10 must jump through an aperture in a structure (e.g.a window). If the vertical portion of the trajectory were leftuncontrolled, the robot might be able to fling itself at the window, butthere would be no assurance that the robot 10 would pass through theopening. Rather, it could strike above, or below, the opening.

Other modes of locomotion are also possible for the robot 50 asillustrated by FIGS. 2 and 3. For instance, a set of legs 20D, 20E, and20F (FIG. 2) can be attached to the body 18 in such a manner that therobot 50 pivots about the distal end 26 of one of the legs 20 whenanother of the legs propels the robot 50. More particularly, the legs20D, 20E, and 20F could be distributed about the body 18 in such amanner that they all lie in a plane that is generally perpendicular tothe surface 12 and extending through the center of gravity 28. In thecurrent embodiment, the robot 50 rests on a pair of legs 20D and 20F,for example, and may be wide enough that the robot 50 is stable andcannot topple into, or out of, the page as seen in FIG. 2.

When it is desired for the robot 50 to move, one of the legs is actuatedso that it imparts an acceleration to the robot 50. Arrow 30 in FIG. 2Ashows leg 20D propelling the robot 50 along the longitudinal axis 22D.The imparted acceleration is enough to lift leg 20D from the surface 12,but not necessarily enough to propel the robot 50 (i.e. the leg 20F)from the surface 12. The resulting moment acting about the distal end26F of leg 20F causes the robot 50 to pivot or rotate about the distalend 26F as shown by the arrow 32. In FIG. 2B, the continued rotation ofthe robot 50 about the distal end 26F is indicated by arrow 34 as theleg 20D approaches a position generally above the body 18. Then, in FIG.2C the rotation can stop as leg 20E pivots into contact with the surface12. Thus, the leg 20D has caused the robot 50 to pivot about the distalend 26F of another leg 20F to traverse the surface 12. That is, therobot 50 rolls up and over leg 26F because leg 20D imparted anacceleration to the robot 50.

It is preferred for the robot 50 to continue rolling leg-over-leg totraverse the surface 12, but the robot 50 can be configured to stopafter each incremental rotation and re-assess its position. Thecontinuous leg-over-leg rolling can be affected by timing a series ofleg 20 actuations (e.g. legs 20D, 20E, 20F and so forth) to occur aseach incremental rotation comes to a finish. In this manner, themomentum of the robot 50 is preserved thereby lowering the amount offuel required to traverse the surface. As illustrated in FIG. 2, therobot 50 is therefore able to roll leg-over-leg along the surface 12 aswell as hopping about the surface 12.

FIG. 3 illustrates another mode of locomotion of the robot 60. FIG. 3Ashows the robot 60 viewed directly from above with legs 20G, 20H, and201 extending from the lower half of the body 18. Legs 20G and 20H areeach shown (via arrows 36 and 38 respectively) imparting acceleration tothe robot 60. The accelerations 36 and 38 combine to produce a netacceleration 40 acting up and through the center of gravity 28 of therobot 60. The net acceleration 40 causes both legs 20G and 20H to risefrom the surface 12 with the remaining leg 20I remaining in contact withthe surface 12. Because the net acceleration 40 is directed at an acuteangle with respect to the leg 20I, the robot 60 responds by pivotingabout the distal end 26I of the leg 20I as shown by the arrow 42 (seeFIG. 3B). As a result, the robot 60 takes a small “step” toward the sideof the body 18 generally in the direction of the force 40. The operationcan then be repeated with a different pair of legs 20 to cause the robot60 to step in another direction. By repetition of this operation, therobot 60 can be made to appear to walk (or colloquially to “waddle” fromside to side) in any direction. Such actions are particularly useful forre-orientating the robot 60 and for making incremental adjustments tothe location of the robot 60.

Turning now to FIG. 4, another preferred embodiment of the presentinvention is shown. The robot 110 includes a plurality of legs 120distributed about its periphery. More particularly, a pair of the legs120A and 120B are shown with a cover 141 of the legs 120 removed so thatthe internal components of the legs 120A and 120B are shown. Theinternal components of the legs 120 include an actuator “foot” 142 andan actuator piston 144 coupled by a spring 146. Also shown inside theleg is a cylinder or gas expansion chamber 148. The foot 142 is adaptedto rest on, and exert a force against, a surface (not shown). Generally,the foot 142 will rest on the surface at an acute angle so that one side150 of the leg 120, or another side of the leg 120, will contact thesurface. The side 150 may be roughened or otherwise treated to improvetraction with the surface so that when the leg 120 is actuated little,or no, slipping of the leg 120 occurs. The piston 144 fits in, andslides along, the cylinder 148. Additional, a seal may be placed aroundthe piston 144 to prevent gas from leaking out of the cylinder 148prematurely during operation.

In operation, fuel from a tank (to be discussed with reference to FIG.6) is rapidly converted to a hot gas. The pressurized gas drives thepiston 144 out toward the distal end 126 of the cylinder 148 and leg120. As the piston 144 accelerates, it compresses the spring 146 therebycausing the spring 146 to exert a force on the foot 142. As the piston144 moves past a location along the cylinder 148, it exposes a vent hole(or holes) on the side of the cylinder 148 through which the hot gasesgenerated in the proximal end of the leg 126 are released. Theuncovering of the vent holes restores the atmospheric pressure (orvacuum if operating in space) inside the leg 126, which allows the foot142, in turn, to push against the surface thereby causing an oppositereaction on the robot 110 and to simultaneously release the springtension. Thus, depending on the gas pressure and flow rate, the actuatoraccelerates the robot 110 sufficiently to lift the leg 120 from thesurface. More particularly, the acceleration (optionally combined withthe acceleration provided by other legs 120) can be enough to cause theentire robot 110 to leave the surface. Thus, the robot 110 of FIG. 4 canalso hop. As the robot 110 lands after a hop, it will roll to a stopwhere it will generally rest on a set of legs 120 different than the setof legs 120 upon which it rested before the hop. Because the pluralityof legs 120 allows the robot to roll the software controlling the robot110 need not be complicated by routines necessary to predict the robot's10 orientation after a move or necessary to maintain the robot 110 in astable (or meta-stable) orientation. Rather, a preferred control systemneed only determine the current orientation with sufficient accuracy toselect the legs 120 that will cause motion in the next desireddirection. Moreover, if the robot 110 overshoots, or undershoots, itstargeted location, the control system need only command another hop tobring the robot 110 to the target location. Accordingly, robots 110constructed in accordance with the present invention are far simpler tobuild, program, and operate than those constructed in accordance withprevious approaches to robot locomotion.

Furthermore, if the robot 110 becomes trapped, or stuck, a random seriesof hops may be sufficient to free the robot 110. Also, because the robot110 will appear to move in an unpredictable fashion (jumping first oneway, then another), it will be quite difficult for hostile forces tocapture or disable the robot 110. Further, the apparently chaotic pathfollowed by the robot 110 (with successive hops in rapid succession) maybe sufficient to disorient or distract hostile forces in enclosedvolumes (e.g. rooms). In fact, an operator of a robot 110 that has anonboard camera could purposely target a member of a hostile force withthe robot 110 itself.

The spherical body 118 of the robot 110 illustrated in FIG. 4 alsoprovides several other practical advantages. First, the sphere 118allows ample stowage room for electronics, fuel supplies, and othersystems and components that are best positioned onboard the robot 110.Further, the spherical body 118 can be configured to split open into twohalves so that access can be had to the interior volume for changingbatteries and refilling the fuel tank, for example.

Turning now to FIGS. 5A and 5B, a leg 220 of a preferred embodiment ofthe present invention is illustrated in simplified cross section. FIG.5A shows the leg 220 in a retracted position and FIG. 5B shows the leg220 in an extended state. In the current embodiment, the robot is madeto hop by rapidly driving the leg 220 from the retracted state of FIG.5A to the extended state shown in FIG. 5B. While the leg is off of thesurface, the leg retracts to the retracted position of FIG. 5A, therebyreadying the leg 220 (and the robot) for the impending landing and forthe next hop (should that leg 220 be needed for the next hop). The leg220 includes a body 251, a foot 242, a piston 244, a connecting rod 245,a spring 246, an expansion chamber 248, a hot gas inlet port 254, and anexhaust outlet port 256.

Preferably the foot 242 is semispherical so that no matter what theorientation of the leg 220 relative to the surface may happen to be, thefoot 242 can engage the surface and exert a force against it to propelthe robot. The connecting rod 245 couples the foot 242 and the piston244. The piston 244 slides within the expansion chamber 248 between theproximal 224 and distal 226 ends of the leg 220. Of course, the innerwalls of the body 251 and the piston 244 define the expansion chamber248. The spring is attached to the inner wall of the body 251 at thedistal end 226 of the body and is also attached to the piston 244.Because the spring is pre-loaded in its extended form, the spring 246biases the leg (i.e. the piston 244, connecting rod 245, and foot 242assembly) in the retracted position, at atmospheric (i.e. ambient)pressure. The gas ports 254 and 256 are located, respectively at theproximal end of the expansion chamber 248 and near the distal end of theexpansion chamber 248. Further, the exhaust port 256 is spaced apartfrom the distal end of the expansion chamber 248 by a distance at leastequal to the compressed length of the spring 246 and the height of thepiston 244.

In operation, hot pressurized gas is ported to the inlet 254 whereuponit enters the expansion chamber 248 and begins building pressure in theexpansion chamber 248. Since the foot 242 is constrained by the surface(or eventually contacts the surface and becomes constrained if,initially, the leg 220 was over a hole or depression in the surface) thepressure of the hot gas acts against the proximal end of the expansionchamber 248 thereby causing the body 251 and the robot to acceleratealong the longitudinal axis 222 in the proximal direction. The resultingrelative movement between the body 251 and the piston 244 compresses thespring 246. Shortly before the exhaust port 256 is uncovered, the gassupply to the intake port 254 is isolated. The body 251 then moves farenough relative to the piston 244 so that the piston 244 uncovers theexhaust port 256 and allows the expanded gas to escape through theexhaust port 256. At about this time, the leg 220 reaches the extendedposition of FIG. 5B. With the gas escaping, the pressure in the chamber248 rapidly begins to decrease thereby allowing the spring 246 to expandagainst the piston 244. As a result, the leg 220 begins to retract. Ithas been found in operation that the gas dynamics within the expansionchamber 248 and the spring dynamics can be matched so as to optimize theperformance and efficiency of the leg 220. Further, the spring 244 canbe tuned to provide damping as the piston reaches the distal end of theexpansion chamber 248.

Turning now to FIG. 6, FIG. 6 illustrates a schematic of a fuelsubsystem 353 and leg control subsystem 353 of the robot illustrated inFIG. 4. Generally, the fuel subsystem 351 feeds an actuator 350 for eachof the legs 320A to 320T and includes a fuel tank 352, a control valve364 for each of the actuators 350, and a catalytic gas generator 366 foreach actuator 350. In the alternative, the robot 310 can include acommon gas generator that feeds hot gas to each of the actuators 350through the individual control valves 364. The leg control subsystemincludes an inclinometer 354 (or alternatively a gyroscope 356 orinfrared proximity sensors or weight sensors 358 on the legs 320) orother equivalents for determining which of the legs 320 are resting onthe surface. The control subsystem also includes, or is in communicationwith, a guidance, navigation, and control (GN&C) subsystem 360 thatamong other things may determine which direction to move the robot 310.A leg controller 362 is also shown.

The inclinometer 354 allows the controller to determine which legs areresting on the surface based on knowledge of the configuration of therobot 310. In the alternative, the weight sensors 358 can allow thecontroller 362 to make a direct determination of which legs arecontacting the surface. The controller 362 also communicates with thecontrol valves 364. The control valves, of course, provide thecapability to flow fuel from the fuel tank 352 to the gas generators 366wherein the fuel decomposes exothermically to form a hot gas. The hotgas then flows into the actuator 350 for imparting an acceleration tothe robot 310. By controlling how far the valve opens it is possible toselect the amount of acceleration provided by each of the actuators320A.

In operation, the robot 320 of the current embodiment functions asfollows. The controller 362 receives a command from the GN&C subsystemsto move the robot 310. From the inclinometer 354 data, the controller362 determines which of the legs are resting on the surface and may thusparticipate in the move. Given the desired direction, distance, andheight of the hop, the controller 362 selects the leg(s) 320 capable ofmoving the robot 310 to the desired position. Of course, the movementcan be by way of a combination of “hops, “steps,” or “pivots” aspreviously described. In accordance with the mode of locomotion selectedand the orientation of the selected legs 320, the controller 362calculates a combination of accelerations that will propel the robot tothe target position. The controller 362 then opens each affected valve364 by an amount that will cause the associated leg 320 to produce thedesired acceleration for the particular leg. Fuel then flows from thetank 352 to the appropriate gas generators 366 where it decomposes andflows into the actuators 350 as a pressurized gas. In the actuators 350,the resulting hot gas causes the actuator 350 to impart the desiredacceleration to the robot 310. Since the selected actuators 350 operateat approximately the same time, the net result of the accelerations fromeach of the legs 320 is an overall acceleration for the robot 310 in thedesired direction and of sufficient magnitude to cause the robot to moveto the target location. If the robot overshoots, undershoots, orotherwise misses the target, the controller repeats the process untilthe position of the robot 310 is close enough to the target positionthat no further movement is desired.

In one preferred embodiment, the fuel tank 352 is about 3 to 4 inches indiameter is positioned in the spherical body 318 and contains enoughhydrogen peroxide fuel to sustain operations for over 8 hours ofgenerally continuous operation. The use of a monopropellant simplifiesthe operation and design of the robot 310 because an oxidizer subsystemis not required. Nor is an ignition source necessary. Also, the use of amonopropellant allows the robot 310 to operate underwater and in spaceor other hostile environments. Moreover, the high power density ofhydrogen peroxide (in particular) allows the robot 310 to move asrapidly as the fuel flow rate and gas generator will allow.

As implied above, the present invention also provides methods fortraversing a surface. One method 400 in accordance with a preferredembodiment of the present invention is illustrated in FIG. 7. The method400 includes selecting a target position for a robot in operation 410.The legs (or actuators) of the robot which are contacting the surfaceare then determined. See operation 412. From these available actuators,a group of actuators is selected that are capable of moving the robot tothe new position as in operation 414. Usually, the legs that are thefarthest away from the target position are used. A determination is maderegarding how much acceleration should be imparted to the robot fromeach of the selected legs. See operation 416. In operation 418, theactuators are used to impart the desired accelerations to the robotthereby creating a net acceleration on the robot. The imparted netacceleration causes the robot to traverse the surface as in operation420 by hopping, stepping, or rotating depending on the selected mode oflocomotion. The new position of the robot is then determined inoperation 422 and if desired, the method repeats as indicated byoperation 424. In particular, if the new position is not close enough tothe target position (because, for example, an actuator failed) thenalternative combinations of the legs can be employed to re-position therobot.

In view of the foregoing, it will be seen that the several advantages ofthe invention are achieved and attained. Vehicles constructed inaccordance with the principals of the present invention are able to“hop” over obstacles that would immobilize conventional vehicles. Thus,the vehicles can maneuver over rough terrain and even climb stairs.Likewise, vehicles provided by the present invention can free themselvesfrom traps by executing a series of random hops until an escape path isfound. Further, hopping vehicles provided by the present invention caneven be thrown through a window to reconnoiter a room or a building. Thesomewhat “jerky” motion caused by the hops of these vehicles makes themdifficult to disable or capture. While, such vehicles can carrysurveillance or communication equipment, they can also carry anexplosive payload for destroying a target (or itself if it is capturedor disabled).

Further, because the robots of the present invention rest on their legs,they need expend no energy while loitering. Additionally, because themechanical subsystems are simple in comparison to other robot designs,and because the algorithms used to control the robot are relativelysimple, the robots can readily be scaled up, or down, in size. Plus,because the robots constructed in accordance with the present inventionhave no “up” or “down” they cannot be toppled.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical application to therebyenable others skilled in the art to best utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated.

As various modifications could be made in the constructions and methodsherein described and illustrated without departing from the scope of theinvention, it is intended that all matter contained in the foregoingdescription or shown in the accompanying drawings shall be interpretedas illustrative rather than limiting. For example, the vehicles providedby the present invention can be autonomous, semi-autonomous, or remotelycontrolled. In other preferred embodiments, the robot uses a compressedgas (e.g. CO2) instead of decomposed fuel to drive the legs of therobot. In still other preferred embodiments, the leg actuators aredriven electrically rather than by a mechanical (fluid) energy source.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims appended heretoand their equivalents.

1. A vehicle comprising: a body; and at least three legs; each legincluding a proximal end coupled to the body, a distal end opposite theproximal end and being adapted to rest on a surface, a longitudinal axisextending along a direction between the proximal and distal ends, and anactuator adapted to impart an acceleration to the vehicle along thelongitudinal axis of the leg that includes the actuator, theacceleration to be large enough to cause the distal end of the leg toleave the surface.
 2. The vehicle according to claim 1, furthercomprising the at least three legs being configured and adapted in amanner so that when an actuator of a leg imparts an acceleration to therobot, the robot pivots about the distal end of at least one of theother legs.
 3. The vehicle according to claim 1, further comprising theactuator being configured and adapted in a manner so that when anactuator of a leg imparts an acceleration to the robot, the distal endof at least one of the other legs leaves the surface.
 4. The vehicleaccording to claim 1, further comprising a power source for theactuators.
 5. The vehicle according to claim 4, wherein the power supplyis an electric power supply.
 6. The vehicle according to claim 4,wherein the power supply is a chemical power supply.
 7. The vehicleaccording to claim 6, wherein the chemical power supply is amonopropellant power supply.
 8. The vehicle according to claim 1, eachactuator further comprising a spring biasing the actuator toward theproximal end of the leg that includes the actuator.
 9. The vehicleaccording to claim 1, wherein the legs are located around the body insuch a manner as to correspond to at least one of the faces or verticesof a Platonic solid.
 10. The vehicle according to claim 9, wherein thenumber of legs equals the number of faces, the coupling of each leg tothe body being at one of the faces.
 11. The vehicle according to claim1, wherein the body is a sphere.
 12. The vehicle according to claim 1,further comprising being a robot.
 13. The vehicle according to claim 1,further comprising being a toy.
 14. The vehicle according to claim 1,the actuators further comprising being adapted and configured for one ofterrestrial, lunar, or Martian gravity.
 15. The vehicle according toclaim 1, wherein the robot having a center of gravity, each of thelongitudinal axis of the legs passing through the center of gravity. 16.The vehicle according to claim 1, wherein the at least three legsincludes one of 4 legs, 6 legs, 8 legs, 12 legs, or 20 legs.